Trapp began working at Messiah in 1972 when she was hired as a part-time physical education instructor and assistant field hockey coach. She was named head coach of the Falcons in 1973, beginning a 39 year-stint as the program's coach.

Her career has rivaled those of legendary coaches in NCAA Athletics history: a career record of 536-179-28. At the time of her retirement in 2011, her victory total was ranked first all-time in NCAA Division III field hockey, and third all-time across all NCAA divisions.